Internet Protocol Version 6 (IPv6) is a new version of the Internet Protocol, designed as the successor to Internet Protocol version 4 (IPv4). Since IPv6 does not support mobility, packets addressed to a mobile IPv6 node (a node that dynamically changes its access point to the Internet) cannot reach the node when it is away from its home link. In order to support mobile IPv6 nodes, Mobile IPv6 (MIPv6) was created. MIPv6 enables mobile IPv6 nodes to remain reachable while they move around in IPv6 networks.
However, there are currently two versions of Internet Protocol in use: the widely used but older Internet Protocol Version 4 (IPv4) and the less used but newer Internet Protocol Version 6 (IPv6). If a mobile IPv6 node moves to an IPv4-only network, the mobile IPv6 node will be unable to continue IPv6 communication with its corresponding IPv6 peers. This is because the originating mobile IPv6 node would first have to communicate with an IPv4-only node, which then would have to communicate with the terminating IPv6 node. This is not supported by either IPv6 or MIPv6. While IPv6 is expected to gradually replace IPv4, the two versions will coexist for a number of years during the transition period. Thus, enabling a mobile IPv6 node to engage in IPv6 communication with other IPv6 nodes, even when the mobile IPv6 node is in an IPv4-only network, is an important concern among users of the Internet.
What is needed are methods and systems for a mobile IPv6 node in an IPv4-only network to engage in IPv6 communication across the IPv4-only network. The methods and systems should not require an upgrade of the IPv4-only network.